TITLE:   GCN CIRCULAR
NUMBER:  31920
SUBJECT: IPN triangulation of GRB 220411A
DATE:    22/04/19 10:07:29 GMT
FROM:    Anna Ridnaia at Ioffe Institute  <ridnaia@mail.ioffe.ru>

A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin
on behalf of the HEND/Mars-Odyssey team,

A. Ridnaia, D. Frederiks, D. Svinkin, A. Lysenko,
and T. Cline on behalf of the Konus-Wind team,

A. Goldstein, M. S. Briggs, and C. Wilson-Hodge
on behalf of the Fermi GBM team,

E. Bozzo and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,

and

W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr,
and A.S. Gardner on on behalf of the GRS-Odyssey GRB team,
report:

The long-duration GRB 220411A
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 31871;
BALROG localization: Kunzweiler et al., GCN Circ. 31872;
AstroSat CZTI detection: Gopalakrishnan et al., GCN Circ. 31879)
was detected by Fermi (GBM trigger 671354405), INTEGRAL (SPI-ACS),
Konus-Wind, Mars-Odyssey (HEND), and AstroSat (CZTI)
at about 26401 s UT (07:20:01).

We have triangulated it to a SPI-ACS-HEND annulus centered at
RA(2000)=149.487 deg (09h 57m 57s)  Dec(2000)=+13.850 deg (+13d 50' 59"),
whose radius is 30.455 +/- 0.229 deg (3 sigma).

The Fermi GBM Final Real-time (GCN Circ. 31871) and
BALROG (GCN Circ. 31872) localizations are consistent with the annulus.
The annulus combined with the BALROG localization
gives the following error box:
------------------------------------------------------------
   RA(2000), deg                 Dec(2000), deg
------------------------------------------------------------
  Center:
   179.643 (11h 58m 34s) +25.001 (+25d 00' 04")
  Corners:
   176.853 (11h 47m 25s) +31.565 (+31d 33' 54")
   176.353 (11h 45m 25s) +31.390 (+31d 23' 26")
   180.657 (12h 02m 38s) +18.050 (+18d 03' 01")
   181.134 (12h 04m 32s) +18.133 (+18d 07' 57")
------------------------------------------------------------
The error box area is 6.4 sq. deg, and its maximum
dimension is 14 deg (the minimum one is 27 arcmin).
The Sun distance was 134 deg.

This box may be improved.

A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB220411_T26405/IPN

The time history and spectrum will be given in forthcoming GCN Circulars.